IIS missing New Web Site option

I've got IIS 5.1 running on my machine with one Web Site (Default Web Site) containing a few virtual directories. I've got one virtual directory running an ASP.net site and it's working fine. I tried to set up another virtual directory to run a classic asp site, but I guess you're not supposed to be able to do that. So I was going to set up a separate web site to run it under, but I can't find the option to do this. I looked around online and it appears that I should have an option when I right-click on the Web Sites folder to create a new web site, but this is absent. The only options in that context menu are "Refresh", "Properties" and "Menu". I can't find the "New Web Site" option anywhere.

Does anyone know why this might be?

Thanks

EDIT:

The issue was I didn't have NTFS permissions set for the website's directory, so it was giving me a no access error. I thought this was to do with IIS as apparently sometimes incorrect settings in IIS can cause this error. Apparently not.